1. Field of the Invention
The present invention relates to a wireless communication control method preferably applied to such a case where various information is transmitted by means of a wireless signal, for example, to construct a local area network (LAN) among a plurality of devices, and a wireless transmission apparatus using this control method.
2. Description of the Related Art
Conventionally, in a relatively small range such as home, office or the like, when a local area network is constructed between a plurality of devices such as various image devices, personal computer machine and its peripheral devices and so on so as to make it possible to transmit data handled by these devices, a wireless signal transmitter/receiver (a wireless transmission apparatus) is connected to each device so as to enable data transmission through wireless transmission, instead of direct connection between respective devices via a signal line.
A local area network is constructed through wireless transmission, thereby making it possible to simplify a system configuration without requiring direct connection between respective devices via a signal line or the like.
In the meantime, in the case where a local area network is constructed by preparing a plurality of wireless transmission apparatuses, if signals are transmitted simultaneously from a plurality of transmission apparatuses, there may be a possibility that a transmission error occurs. Thus, communication between respective transmission apparatuses in the network is required to be access-controlled by means of any method.
As a conventionally known access control method, for example, in a small scale wireless network, there is exemplified a method for unitarily managing communication between respective transmission apparatuses (terminal stations: nodes) in the network by means of a transmission apparatus (a central control station: a route node) being a central part in a start-type connection. For example, there is a method for managing communications in a network by means of polling control. In this method, a central control station in a network transmits a control signal for performing polling sequentially to another node in the network so that the transmission from each node is performed sequentially by means of polling. This polling transmission processing is performed, thereby making it possible to improve transmission efficiency.
However, in the case where a wireless network is constructed via such star-type connection in which a central control station has been allocated, it is required that the central control station must be a station which is capable of directly making wireless communication with all terminal stations in the wireless network. If there exists a station which can not receive a signal to be transmitted from the central control station directly, it is difficult for the terminal station to receive a polling control signal to be transmitted from the central control station, and there exists a terminal station incapable of polling control. Therefore, it is important to select and allocate a central control station when such wireless network is constructed; and there has been a problem that it cannot be easily determined as to which station is selected as the central control station.
In addition, after a central control station has been determined in a conventional wireless network system once, in the case where a terminal station is newly allocated, there has been a problem that the terminal station can be allocated only at a position capable of directly making wireless communication with the central control station. That is, even if a terminal station is allocated at a position incapable of wireless communication with the central control station, that terminal station is incapable of receiving a polling control signal or the like from the central control station. After all, the terminal station is incapable of performing transmission.
An object of the present invention is to easily and properly select a control station when the control station is set, and wireless communication access management is performed under the control of the control station.
As a first aspect of the present invention, there is provided a wireless communication control method for controlling an access of wireless communication between a plurality of communication stations via wireless transmission of a control signal from a control station to a terminal station, in which a communication station selected as a central control station judges a station with which each terminal station in a wireless network is capable of directly making wireless communication; and when it is detected that said each terminal station is capable of making wireless communication with communication stations having many more terminal stations than stations capable of directly making wireless communication with the central control station, a processing for changing the detected terminal station to a central control station is performed.
According to the first aspect of the present invention, there is provided a wireless transmission control method, wherein a station suitable to control each communication station in a wireless network is automatically selected as a central control station.
As a second aspect of the present invention, there is provided a wireless communication control method, wherein after authentication processing for participation has been executed via wireless transmission so as to be connected to an existing wireless network configured under the control of a central control station, in the case where it is judged that the corresponding wireless network does not exist all over available frequency bandwidths, an own station becomes a central control station to set a wireless network.
According to the second aspect of the present invention, there is provided a wireless transmission control method, wherein in the case where there is no other communication station acting as a central control station in the neighborhood, an own station is automatically set to a central control station, making it possible to construct a wireless network.
As the first aspect of the present invention, there is provided a wireless transmission control apparatus for controlling wireless communication at a terminal station in a network, which comprises a communicating means for wireless-transmitting control information for controlling transmission of a radio signal from said terminal station and for receiving a wireless signal transmitted from the terminal station, and a control means for judging a wireless communication state at a terminal station in the network based on a received predetermined signal by said communicating means, and performing transmission control of control information for moving a transmission function of said control information to any terminal station in the network based on the judged communication state.
According to the wireless transmission apparatus of the present invention, when this transmission control apparatus acts as a central control station, if it is judged as to the presence of a station suitable as be a central control station rather than the own station, processing for moving the control function to that station is executed.
As the second aspect of the present invention, there is provided a wireless transmission control apparatus in which wireless communication is performed under the control of a control station in a wireless network, which comprises a communicating means for receiving control information from the control station and transmitting prepared information based on the control information; and a control means for, when the communicating means cannot receive the control information all over available frequency bandwidths by a system, an own station is set as a control station for transmitting control information from the communication means.
According to the second aspect of the present invention, there is provided the wireless transmission control apparatus, wherein in the case where there is no other communication station acting as a central control station in the neighborhood, processing for an own station to be automatically set to a central control station is executed.